The best time to use a sauna depends on what you’re trying to get out of it. For sleep, 1 to 2 hours before bed is ideal. For exercise recovery, a separate session on its own (not immediately before or after a workout) gives you the most benefit with the least downside. For long-term heart health, frequency matters more than timing: people who use a sauna four or more times per week have significantly lower rates of cardiovascular death than those who go once a week.
For Better Sleep: 1 to 2 Hours Before Bed
When you sit in a sauna, your core body temperature rises significantly. After you step out and cool down, that temperature drops, and the drop signals your brain that it’s time for sleep. This mimics your body’s natural circadian rhythm, where core temperature falls in the evening as you prepare for rest. Research on passive body heating found that warming up 1 to 2 hours before bedtime optimized this natural temperature decline, helping people fall asleep faster and sleep more deeply.
If you sauna right before climbing into bed, your body may still be too warm to trigger that sleep signal effectively. Give yourself that cooling window and you’ll notice the difference.
Around Workouts: Timing Matters More Than You’d Think
Using a sauna right before exercise is generally a bad idea. The heat raises your body temperature and causes significant fluid loss through sweat, both of which hurt performance. Studies show that pre-heating decreases the time it takes to reach exhaustion during exercise and makes the same intensity feel harder. If you’re exercising in hot weather after a sauna session, the risk of heat exhaustion goes up considerably.
The one exception: if you’re training for an athletic event in hot conditions, short sauna sessions before workouts over the weeks leading up to competition can help your body acclimate to the heat.
After a workout, the picture is mixed. Regular post-exercise sauna use has been linked to lower cholesterol, lower blood pressure, and better cardiovascular fitness. A small study found that infrared sauna use after endurance training improved recovery of jumping ability and reduced perceived muscle soreness. But a study on swimmers showed that sitting in a sauna after training led to worse performance the next morning, likely due to the added dehydration and thermal stress on top of an already taxed body.
The safest approach for most people is to use the sauna at a different time of day than your workout. If you do combine them, post-exercise is better than pre-exercise, but rehydrate aggressively and don’t expect to perform your best the following day.
For Heart Health: Frequency Over Everything
The cardiovascular benefits of sauna use are dose-dependent, meaning more sessions per week produce better outcomes in a linear fashion. A large prospective cohort study published in BMC Medicine tracked sauna habits and cardiovascular mortality across thousands of participants. Compared to people who used a sauna once per week, those who went two to three times had roughly 29% lower cardiovascular death rates. People who went four to seven times per week had a striking 77% reduction after adjusting for other risk factors like physical activity and socioeconomic status.
Total weekly minutes matter too. Participants who spent more than 45 minutes per week in a sauna had 43% lower cardiovascular mortality compared to those who spent 15 minutes or less per week. A typical session lasts 5 to 20 minutes, so hitting that threshold might mean three sessions of 15 minutes each.
A separate study published in JAMA Internal Medicine found similar patterns for all-cause mortality. Men who used a sauna four to seven times weekly had a 63% lower risk of sudden cardiac death compared to once-a-week users. Sessions longer than 19 minutes were associated with a 52% lower risk compared to sessions under 11 minutes.
Pairing With Cold Exposure
If you’re interested in contrast therapy (alternating between heat and cold), the traditional and most physiologically sound sequence is sauna first, cold water second. Spend 15 to 20 minutes in the sauna, then 1 to 4 minutes in cold water around 50 to 59°F.
The logic behind this order is vascular. Heat causes your blood vessels to expand, increasing circulation throughout your body. When you then plunge into cold water, the sudden constriction creates what researchers describe as a “vascular workout,” a rapid cycling between dilation and constriction that may strengthen cardiovascular function over time. Starting with cold and moving to heat reverses this pattern and doesn’t provide the same preparatory benefit. The heat also activates protective proteins inside your cells that help manage the stress of cold exposure, essentially priming your body for what comes next.
What Happens to Your Body During a Session
Traditional Finnish saunas operate between 180 and 190°F, while infrared saunas run much cooler at 110 to 140°F. Both raise core body temperature, but through different mechanisms: traditional saunas heat the air around you, while infrared saunas use light to warm your body directly.
Your body responds to the heat by increasing heart rate, dilating blood vessels, and sweating heavily. In one study, young men lost an average of 0.65 kg (about 1.4 pounds) of fluid during a 60-minute protocol consisting of four 10-minute sauna sessions at 90°C with 5-minute breaks in between. That weight loss is almost entirely water, not fat, and returns once you rehydrate.
Calorie burn does increase in a sauna, but not as dramatically as some claims suggest. During the first 10 minutes, participants in the same study burned about 73 calories on average. By the fourth 10-minute session, that number climbed to about 131 calories, with larger individuals burning up to 153 calories in a single 10-minute block. These numbers are higher than sitting on a couch but far lower than actual exercise. Sauna is not a meaningful weight loss tool on its own.
The heat also triggers hormonal changes, including increases in growth hormone and cortisol. Higher temperatures and longer sessions produce a stronger cortisol response. However, adding a sauna session after intense exercise doesn’t appear to boost testosterone or growth hormone beyond what the exercise itself already produced.
Who Should Avoid Sauna Use
Most healthy people tolerate saunas well, including pregnant women with uncomplicated pregnancies. But certain cardiovascular conditions make sauna use genuinely risky: unstable angina (chest pain at rest or with minimal activity), a recent heart attack, and severe narrowing of the aortic valve are all clear contraindications.
Alcohol is the other major risk factor. Drinking during sauna use increases the likelihood of dangerous drops in blood pressure, irregular heart rhythms, and sudden death. The small number of acute cardiac events that occur in saunas are disproportionately associated with alcohol consumption.